;---------------
; Assembly Code
;---------------
#define __SFR_OFFSET 0x00
#include "avr/io.h"
;------------------------
.global start
.global led
;------------------------
start:
SBI DDRB, 4 ;set PB4 (D12) as o/p
RET ;return to setup() function
;---------------------------------------------------------------------------
led:
CPI R24, 0x00 ;value in R24 passed by caller compared with 0
BREQ ledOFF ;jump (branch) if equal to subroutine ledOFF
SBI PORTB, 4 ;set D12 to high
RCALL myDelay
RET ;return to loop() function
;---------------------------------------------------------------------------
ledOFF:
CBI PORTB, 4 ;set D12 to low
RCALL myDelay
RET ;return to loop() function
;---------------------------------------------------------------------------
.equ delayVal, 10000 ;initial count value for inner loop
;---------------------------------------------------------------------------
myDelay:
LDI R20, 100 ;initial count value for outer loop
outerLoop:
LDI R30, lo8(delayVal) ;low byte of delayVal in R30
LDI R31, hi8(delayVal) ;high byte of delayVal in R31
innerLoop:
SBIW R30, 1 ;subtract 1 from 16-bit value in R31, R30
BRNE innerLoop ;jump if countVal not equal to 0
;--------------
SUBI R20, 1 ;subtract 1 from R20
BRNE outerLoop ;jump if R20 not equal to 0
RET
;---------------------------------------------------------------------------